equally someone could write a windows driver and the chip would work, no violation of ftdi's IP.
Of course they could, they could join the USB-IF and pay to get their own VID. They could submit their drivers, hardware, and money to Microsoft for WHQL certification they could submit their drivers, hardware, and money to USB-IF and get USB-IF certification. They could provide datasheets, technical support, driver kits, and stamp their own name on the parts and spend 15 years building a reputation for quality and reliability.
But screw that, FTDI can do and pay for all that shit, we will just make some crap that kinda works like an FTDI part and stamp FTDI on the front.